Stable gold(I) complexes with chelate rings: solution studies of bis(phosphino)ethane complexes and X-ray crystal structure of bis[1,2-bis(diphenylphosphino)ethane]gold(I) hexafluoroantimonate–acetone (1/1)

Abstract

Bis-chelated four-co-ordinate gold(I)–phosphine complexes of 1,2-bis(diphenylphosphino)ethane (dppe) and 1,2-bis(diethylphosphino)ethane (depe) exhibit exceptionally high thermodynamic and kinetic stability both in the solid state and in solution at ambient temperatures. Their formation in solution has been studied by conductivity and ³¹P n.m.r. titrations. Complexes of [Au(depe)₂]⁺ and [Au(dppe)₂]⁺ have been prepared and characterized. These species exist in solution even at Au : bis(phosphine) ligand ratios of 1 : 0.75. The mixed species [Au(depe)(dppe)]⁺ exhibited a trans-gold ³¹P^–31P n.m.r. coupling of 52 Hz. The title complex was crystallized and shown by X-ray crystallography to contain gold(I) with a flattened tetrahedral (closely D_2d) co-ordination geometry (P–Au–P, 85–130°) chelated by two dppe ligands with Au–P bond lengths of 2.39–2.42 Å. Crystals are monoclinic, space group P2₁/n. with a= 18.685(2), b= 19.414(2), c= 15.096(1)Å, β= 91.69(1)°, and Z= 4; 4 811 reflections refined to R 0.062.